The present invention is directed to the field of watermarking. It is more specifically directed to electronic watermarking systems.
A technique for embedding (marking) additional information directly in digital contents is proposed as a means for preventing the illegal copying, transfer and re-distribution of the digital contents. Generally, the marking technique can be sorted into a visible data embedding technique and an audible data embedding technique. The electronic watermarking technique, which is an invisible data embedding technique, is distinctive in that additional information can be embedded with no collateral deterioration of the quality of contents, and in that once data is embedded it is difficult to completely erase it. Since the quality is not deteriorated and invisible/inaudible data are embedded, when the contents are to be distributed or when information such as labeling is embedded, it is visually and audibly difficult to determine whether a mark was actually embedded. On the other hand, according to the conventional visible marking, it is easy to intuitively detect the presence of additional information, while the contents are deteriorated. Thus, the positions where marks can be embedded and the applications of the technique are limited. In addition, when JPEG compression is performed for an image for which a visible mark is provided, unwanted image deterioration occurs in the vicinity of the visible mark because the JPEG compression is not suitable for an image that includes a geometric pattern, such as a logo and a character. Therefore, a system having the functions xe2x80x9cembedding a visible markxe2x80x9dxe2x86x92 xe2x80x9cerasing a visible markxe2x80x9dxe2x86x92 xe2x80x9cembedding an invisible markxe2x80x9d is effective in that it is apparent that information is embedded, and the embedding of information can be performed without the quality of the contents being deteriorated.
The conventional visible information embedding techniques are xe2x80x9cColor correct digital watermarking of imagesxe2x80x9d (U.S. Pat. No. 5,530,759) and xe2x80x9cMethod and apparatus for reducing quantization artifacts in a hierarchical image storage and retrieval systemxe2x80x9d (U.S. Pat. No. 5,568,570). According to either method, a function for erasing an embedded visible mark and simultaneously embedding invisible information is not provided.
For the purpose of preventing the illegal copying and transfer of digital contents, there is a scrambling technique xe2x80x9cScrambling Digital Image Data for Copyright Protectionxe2x80x9d (SCIS96-9A). And a technique described in Nikkei Electronics, No. 694, 714 (pp. 17-18), 1997 is proposed as an image distribution system that employs the scrambling technique and the electronic watermarking technique. An outline of this system is shown in FIG. 2. In FIG. 2, scrambling is performed for one part or all of an image to degrade the quality of an image, and when the scrambling is released, the ID number of a user is embedded by the electronic watermarking technique. This system, however, has the following shortcomings. Electronic watermarking information can be erased as is shown in FIG. 3, since the scrambling area and an embedding area do not match, the differences in the images before and after the scrambling is released are acquired so that one part or all of newly embedded electronic watermarking information can be erased. Data can be decoded by using a memory snapshot as is shown in FIG. 4, since the job of releasing the scrambling and the job of embedding electronic watermarking information are not performed in parallel, original image data that is not scrambled and does not include electronic watermarking information can be illegally acquired by obtaining a memory snapshot (damping the memory during the scramble release process).
To resolve the above shortcomings, it is one object of the present invention to provide an electronic watermarking system and method, and a storage medium including a program for electronic watermarking, that simultaneously and in parallel performs the deletion of additional information from the contents embedded additional information and embeds new additional information.
It is another object of the present invention to provide a method and a system that impartially perform the deletion of a visible mark and the embedding of an invisible mark.
It is an additional object of the present invention to provide a method and a system that make it difficult to acquire original image data when neither a visible mark nor an invisible mark is embedded, even when a memory snapshot is acquired during a process for deleting a visible mark and embedding an invisible mark.
It is a further object of the present invention to provide a contents distribution system and an electronic fingerprinting system that ensure the collection of a charge imposed for the use of the contents.
It is still another object of the present invention to provide a contents distribution system that efficiently arranges a plurality of content sets and distributes them.
To achieve the objects, a method is employed for changing a marking method in accordance with the form used for the employment of digital contents and a change in the possession state, and for embedding other information.